The invention relates to an attachable/detachable process cartridge, an attachable/detachable drum cartridge, an attachable/detachable developer cartridge, and an image forming device capable of employing an attachable/detachable process cartridge, an attachable/detachable drum cartridge, and/or an attachable/detachable developer cartridge.
Electrostatographic image forming devices may include an optical system, a photosensitive device (e.g., a photosensitive drum), a charging device arranged in the vicinity of the photosensitive device, a developer device (e.g., developer roller), a transfer device (e.g., transfer roller), and a cleaning means. In general, electrostatographic image forming devices record images by forming an electrostatic latent image on a photosensitive device, forming a developer image by supplying developer to the formed electrostatic latent image on the photosensitive device, and transferring the developer image onto a recording medium. More particularly, for example, to form an image on a recording medium, the surface of the photosensitive drum is uniformly charged by the charging device before the surface is irradiated with a laser beam so as to form an electrostatic latent image corresponding to the image to be formed on the photosensitive drum. The latent image is then developed using a developer supplied by the developer roller such that a developer image is formed on the photosensitive drum. The developer image is then transferred to the recording medium by the transfer roller. After the visible image is transferred most, and preferably all, of any toner remaining on the photosensitive body is removed by the cleaning means.
In many of these image formation devices, many of the image forming components, such as, the photosensitive device, the charging device, the developer roller, the transfer roller and/or the cleaning means are provided, for example, in a process cartridge that is attachable to/detachable from the image forming device. Examples of such a process cartridge are disclosed in, for example, U.S. Pat. Nos. 6,041,203 and 6,546,217. Such process cartridges may be employed to facilitate, for example, replacement and/or maintenance operations of one or more of the components included in the process cartridge.
Process cartridges generally include a casing, in which the components of the process cartridge are housed, and on which a plurality of electrodes and driving gears are arranged. One of these electrodes may serve as a ground connection and another of these electrodes may feed electric power, from a power source arranged in the main body of the image forming device, to various components of the process cartridge. The driving gears interact with gears and/or members of the image forming device in order to drive various components of the process cartridge.
Image forming devices which employ such attachable/detachable process cartridges generally have an internal space or pathway allocated for attaching and detaching the process cartridge to and from the image forming device. Generally, when such process cartridges are attached to the image forming device, the process cartridge is arranged within a cavity of the image forming device such that various components of the process cartridge can effectively communicate with other components of the image forming device. When such attachable/detachable process cartridges are being arranged in or removed from the image forming device, exposed portions of the process cartridge may rub against exposed portions of the image forming device located along and around the internal space or pathway allocated for installing and removing the process cartridge. While such image forming devices generally include some form of a guiding mechanism (e.g., a groove) for guiding the process cartridge in and out of the image forming device, contact between exposed portions of the process cartridge and the image forming device may occur at least until the process cartridge is engaged with the guiding mechanism. Further, even when guide grooves are provided, some guide grooves are not restrictive enough to prevent such undesirable contact. Thus, generally, at least portions of the process cartridge that are first to enter the image forming device during attachment of the process cartridge (i.e., portions of the process cartridge which are removed last during detachment of the process cartridge), are generally prone to rubbing or undesirable, and possibly damaging, contact with the image forming device.
While some portions of the process cartridge are formed so as to be a protective body for components of the process cartridge, some portions and/or components of the process cartridge are intentionally exposed so that they can contact and work with components of the image forming device when the process cartridge is arranged in the image forming device. Such exposed portions that are to interact with other components may be damaged by the rubbing that generally occurs between the exposed portions and the image forming device during installation and removal of the process cartridge to/from the image forming device. In particular, if, for example, an electrode arranged on an outer surface of the process cartridge is damaged by such rubbing, the process cartridge and/or the image forming device may work improperly.
In some cases, a shutter-like cover that opens to expose, for example, the electrode when the process cartridge is set in an arranged position within the image forming device may be provided in order to reduce, and preferably prevent damage to the exposed portion. It may not be desirable, however, to provide such a shutter-like mechanism at least because of the likely increase in cost and/or size of the process cartridge and/or image forming device.
In particular, there is an increased demand for smaller and smaller image forming devices. To meet this increasing demand, smaller process cartridges must also be provided. At first glance, reducing the size of a process cartridge and/or image forming device may appear to be a straight forward task (e.g., reduce a size of all the components by X%). However, many factors and/or needs aggravate this deceivingly simple task and, those skilled in the art understand that, in fact, various design considerations and requirements make the process quite complex. Further, it is to be appreciated that, in recent years, the overall size of image forming devices and process cartridges has already been reduced substantially and for practicality purposes, there are some “minimum size” restraints on certain components of an image forming device and/or process cartridge. Thus, the playing field (i.e., amount of free/excess space available) has already been reduced substantially. Accordingly, those skilled in the art understand that the task of designing and implementing even smaller image forming devices and even smaller process cartridges while still providing practical devices and cartridges requires extensive experiment, thought and creativity.